Modern computer systems provide different means for controlling access to resources. File systems are a good example of such access control systems. For example, the UNIX® file system provides different levels of access controls to individual files, based on whether the user is an owner of the file, in the same group as the file, or someone else. (UNIX is a registered trademark of the Open Group.) Within each level (owner, group, or other), access control can include distinct levels of control to read, write, and execute the file. A user might grant himself or herself permission to read and write to the file, grant users in the same group permission to read the file, but not write to it, and grant others no permissions at all.
But these permissions are constant in time. The UNIX file system does not provide any ability to control access to files based on time.
A need remains for a way to provide for access control to files and other resources that addresses these and other problems associated with the prior art.